恭賀本中心郭俊翔老師榮獲科技部優秀年輕學者研究計畫！

2021-07-19 週一

米崙斷層區域強地動與場址效應觀測與分析

花蓮米崙斷層於1951年及2018年兩次錯動均造成花蓮市嚴重災害，且目前的科學證據指出米崙斷層之再現週期極可能僅約67年，代表未來的50年仍有53%的錯動機率。

2018年花蓮地震（MW 6.4）並不算大規模強震，但因米崙斷層通過花蓮市區，仍造成頗為嚴重之災害。而米崙斷層沿線距離5公里內的測站幾乎都記錄到速度脈衝，其最大PGV振幅幾乎達到150 cm/s，且脈衝週期約在2秒至3秒，造成此週期的譜加速度值明顯高於現行耐震規範中之設計值。

因此本計畫從地震防災角度著手，規劃三個研究課題：

研究課題一、預計在兩口米崙斷層科學鑽井裝設井下地震儀，本計畫負責各裝設兩部淺部強震儀，觀測地表及近地表強地動特性及場址效應的影響
研究課題二、利用微地動陣列法與速度井測法建立井下地震儀觀測場址的詳細淺層波速構造
研究課題三、使用既有和未來觀測所得資料詳細分析花蓮地區的強地動特性，盼能對本區域的地震防災及耐震規範之不足之處給予建議。也希望藉著與其他相關研究團隊的合作，能加強震源物理與強地動研究間的相互合作，能將臺灣的理論地震學與工程地震學研究同時往前推進。

The Milun Fault sliped in 1951 and 2018 and caused serious seismic hazards in the Hualien City. The current scientific evidence indicates the reoccurrence interval of the Milun Fault may be as short as 67 years and this means the probability of next slip is 53% within 50 years from now.

The last event in 2018 was a medium magnitude earthquake but still made serious damage because it goes throught the Hualien City. All stations within 5 km from the fault recorded pulse-like velocities with a PGV of near 150 cm/s and periods of 2 sec to 3 sec. The observed accelerations were therefore higher than the current design spectrum at long period.

We propose three topics in this project from the aspect of seismic hazard prevention.

The topic one is to install two downhole arrays in the boreholes next to the Milun Fault. We will install two downhole accelerometers in the two arrays for monitoring strong motions and site response of the near surface. The topic two is to study detail near surface velocity structure by microtremor arrays and velocity logging. We will analyze existing strong motion recordings and those will be recorded by the expected network to further understand ground motion characteristics under the topic three, to give comments for seismic hazard prevention and seismic design code in the area.

Hopefully we may promote research on both seismology and engineering seismology in Taiwan by the collaboration between earthquake physics and strong motions.

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